This invention is directed to a D.C. potential controller and in particular to a D.C. potential controller for regulating the magnitude and polarity of a potential applied to a D.C. drive motor to control the driving thereof. While D.C. potential controller arrangements for use in driving D.C. motor driven toys such as electric trains, slide cars and the like have taken on various forms, simplified control arrangements wherein a single movable element is adapted to selectively apply and determine the magnitude and polarity of the D.C. potential applied to the drive motor have been less than completely satisfactory due to the numerous moving parts and complexity required to effect same. Accordingly, a simple D.C. potential contoller utilizing a single moving element for selectively applying and varying the magnitude and polarity of a D.C. potential to be applied to a D.C. drive motor is desired.